docs: def resolve_polytomies(self):
          '''Arbitrarily resolve polytomies below this ``Node`` with 0-lengthed edges.'''
          q = deque(); q.append(self)
          while len(q) != 0:
              node = q.popleft()
              while len(node.children) > 2:
                  c1 = node.children.pop(); c2 = node.children.pop()
                  nn = Node(edge_length=0); node.add_child(nn)
                  nn.add_child(c1); nn.add_child(c2)
              q.extend(node.children)